Lift truck



Ami] 23, 1940. E L DUNHAM 2,197,926

' LIFT y TRUCK Filed Aug. 8, 195s 15 sheets-sheet 5 April 23, 1,940. E. J. DUNHAM j 2,197,926' LIFT TRUCK Filed Aug. 8, 1936 13 Sheets-Sheet 4 K pril Y23, 1940. E. J. DUNHAM LIFT TRUCK Filed Aug. 8, 1936 13 Sheets-Sheet 5 April 23,

E. J. DUNHAM LIFT TRUCK File'd Aug. 8, 19:56

13 sheets-sheet s April 23, 1940. E. J. DUNHAM 2,197,926 Y LIFT TRUCK.

FiledvAug. -8, 1936 13 Sheets-Sheet 7 (Eig I v #n v v w62/ April 23, 1940.v E, 1 DUNHAM 2,197,926

LIFT TRUCK' Filed Aug. 8, 1936 13 Sheets-Sheet 8 'NEL/ TRM I April 23, 1940.

E. J. DUN HAM LIFT TRUCK Filed Aug. s, 193e 1s sneet'sl-sneet' 9 l n 2H,

Anil 23; 1940- E. J. DUNHAM 2,197,926

' LIFT TRUCK Filed Aug. 8, 1936 1 im 352 362 '7g' I ff, 5l

April 23. 1940. E, J, DUNHAM 2,197,926

LIFT TRUCK Filed Aug. 8, 1936 13 Sheets-Sheet 11 April 23, 1940. E, 4, UNHAM 197,926 1.1m'.` TRUCK Filed Aug. 8, 1936 15 Sheets-Sheet 12` APY 273, 1940- J. DUNHAM 2,197,926

' LLM' TRUCK Filed Aug. 8, 1936 13 Sheets-Sheet l5 Patented Apr. 23, 1940 UNITED .STATES LIFT 'rauen Application August 8, 1936, SeriallvNo. 94,926

7 Claims.

A This invention relates to lift trucks, and more particularly is directed to improvements in the construction and operation of lift trucks of the type disclosed in United States Letters Patent 5 Nos. 1,707,428 and 1,986,134, issued April 2, 1929, and January 1, 1935, respectively, to Robert J. Burrows, and to Burrows and Williams.

The invention is primarily concerned with selft propelled lift trucks such as are now commonly l used in warehouses, manufacturing plants, wharves, and the like to lift and transport heavy ,ggds of merchandise and stock about the prem- Trucks of this class are usually either of the l electric motor propulsion type, deriving their energy from storage batteries, or internal combustion engine propulsion type, similar in some respects to a tractor. In the instant case, the invention is directed to the internal combustion 2p engine type of truck, and primarily contemplates certain improvements and modiiications in design and construction that will facilitate easy intzii quietoperation of the truck under al1 conons.

Y 25 The presentinvention has for its primary object a design of lift truck that will meet the demands of the industry for a heavy-duty low-lift truck with sulclent power to meet all ordinary operating conditions and with full load ramp *3c characteristics on ramps ordinarily encountered ed only when in "neutral driving position, and no o change can be made during driving of the truck. The provision for two speeds is highly desirable in plants where long hauls are made, and the truck is then capable of returning empty at high speed. The low speed is used on ramps and in 5' congested operating locations, such as aisles in shops and warehouses, where a higher speed 'is both impractical and undesirable.

Another feature of the present invention is the novel designer steering mechanism employed 50 when a six wheel truck for heavy vloads is provided. In such -a construction, I provide a sixwheel machine in which all of the Wheels act as steering wheels when a turn isto be made. The iront wheel suspension consists of four wheels 5'5- which are so mounted as to impart great flexibility y or reverse speeds can be obtained.

(on aiol to the machine, and to relieve the frame of the machine from any severe strains when passing over uneven road surfaces. Each set of wheels is independent as the front and rear wheels of the four-wheeled front truck on each side of the 5 frame are mounted on a single rocker arm which is pivoted to the frame intermediate the wheels. Thus all four wheels remain in contact when the machine passes over uneven floors, which greatly assists in proper weight distribution and substan- 1@ tially equalizes tire wear.

Another feature of the present invention re sides in the hydraulic system used for controlling lifting and lowering of the load platform..

In the present. invention, this comprises a pump i5 driven directly from the internal combustion engine and connected through exible.' pipes to a balanced slide valve mounted on the lift cylinder. The piston rod in the cylinder hasfa straight gear rack on its `outer end which engages a fan- 20 shaped gear segment connected through a shaft directly to the levers and linkage which raises the load. The pump has been especially designed for'the type of service encountered and is mounted directly on the transmission case, thus eliminating any misalignment which might be occasioned by couplings or the like. Preferably, I employ double lift cylinders in order to equalize the lift on opposite sides of the platform, and utilize a simplified system of interconnection between the lift cylinders so that only a single control valve is required. The mechanism which controls operation of the valve is automatically returned to neutral position when the platform reaches the upper and lower limits of movement so that no possibility of over-stressing the raising and lowering mechanism is produced.

In order to simplify the control of the truck, I have provided a singl'elever which controls forward and reverse engagement of thegears, and o also controls the main drive clutch and the throttle control for the engine. This lever is mounted K for easy operation on the dash board of the vehicle and is so arranged that the main clutch must be disengaged before selection of forward Still another object of the present invention is 4the provision of a novel drive connection between the engine and the driving axle, this connection 'including a four-pinion differential especially de-- 50 of the parts for servicing and simplicity of design of the majority of parts so that they are capable of economical development.

-Other features and advantages ofthe present truck construction will be more apparent from the following detailed description, which, taken in conjunction with the accompanying drawings will disclose to those skilled in the art the particular details of construction and operation of a preferred form of the present invention.

In the drawings:

Figure 1 is a perspective view of the truck with the platform in lowered position;

Figure 2 is an end elevational view of the truck showing the operators platform;

Figure 3 is a detailed perspective view showing the control mechanism for controlling the various driving and lifting operations of the truck;

Figure 4 is a sectional View through the transmission showing the clutching arrangements for controlling selection of the various speeds of operation;

Figure 5 is a sectional view through the driving connection between the transmission and the differential on the driving axle, and also showing details of the brake construction;

Figure 6 is a sectional view through a portion of the driving axle;

Figure '7 is a sectional view showing the connection between the oil pump and the transmission; Y

Figure 8 is a side elevational view of the lift lever control;

Figure 9 is an end elevational view of the mechanism shown in Figure 8;

. Figure 10 is a top view of the mechanism shown in Figure 8;

Figure 11 is a side elevational view-of the main control lever mechanism;

Figure 12 is a top view of the same mechanism;

Figure 12A is a front elevational view of the plate frame for` the lever;

Figure 13 shows indetail the platform control;

Figure 14 is a section taken lsubstantially on line Ill-I4 of Figure 16; 4

Figure 15 is a figure taken substantially on line I5-I5 of Figure 16;

Figure 16 is an end elevationalview of the lift valve construction;

Figure 17 is a perspective view showing the front truck mounting for the steering wheels;I

Figure 18 is a diagrammatic view showing the steering mechanism for a four-wheeled truck;

Figure 19 isa diagrammatic illustration of the steering linkage for a six-wheeled truck; and

Figure 20 is a perspective view showing the arrangement of the lift cylinders and the'end construction of the transmission unit.

Referring now in detail to the drawings, and more particularly to Figures 1 and 2, the lift truck is indicated generally by the numeral 5 and comprises a load platform 6 mounted over a front wheel 4truck assembly indicated at l, and adapted to be raised and lowered by rotation of the arms 8 connected to the underside of the platform and controlled by movement of the piston within lift cylinder and vthe lift cylinder 9, as described in detail in the above mentioned patents.V

The engine for the truck is mounted beneath the hood I0, which is formed in two sections II and I2, the section II being hinged at I3 so that it can be opened for inspection and servicing of the engine, and being held in closed position by the overhanging clamps I4 carried by the upright control panel I5 extending vertically at the forward end of the engine. Suitable side plates I6 enclose the sides of the engine and the operating mechanism and protect'the mechanism from mechanical injury. The operators platform is indicated at I8 and is preferably rounded in order to eliminate any sharp corners so that the truck can readily be maneuvered in narrow aisles. Similarly, the forward end of the truck is tapered for maneuvering about sharp corners, and to prevent cornerwise abutment.. The main drive wheels, resiliently tired, are indicated at I9 -and are mounted beneath the engine and forwardly of the operators platform I8.

Referring more particularly to Figure 2, the control panel is provided with a suitable opening through whichextends the radiator l20 for the engine of the truck, the radiator being mounted in suitable supporting members 22 and having protecting guard strips 23 over the outer face thereof. at 24 and a suitable drain cockis provided Aat 25 shown in Figure 1, as is the customary practice. The vehicle is steered by means of thehand wheel 26 mounted on a horizontal axisand adapted to be rotated by the operator standing on the platform I8. Through suitable gear means, the

rotation of the hand wheel effects corresponding.

rotation of, the shaft 2'I to cooperate the steering mechanism, which will be described in more -detail in connection with Figures 19 and 20,

The operators platform I8 is preferably covered withl a sponge rubber matting 28 for cushioning the operator against any bumping or vibration of the vehicle, and is provided with the brake pedal 29 which is normally urged -'nto brake-setting position and must be moved down- An inletforthe radiator is indicated wardly into a position .flush with the platform in order to effect release of the band brake members 3l! and 32 appearing in the cut-out portion of the panel I5 indicated at' 33 in- Figure 2. A suitable starter button 34 is provided to eliminate hand cranking of -the engine since this has been found undesirable and safety requirements demand that automatic starting be provided. An' instrument housing 35 is mounted below the steering wheel 26 and preferably contains an ammeter 36 indi-- eating the condition of the battery, and any other A suitable instruments, such as the horn button 31. At the right hand side of the control panel I5 and adjacent the top thereof, is a gear shift inem- -ber 38 which extends forwardly through the panel and is movable toward and away from the panel to effect shifting of the drive from low to high speed. Directly below the member 38 is the frame' plate 39`which is suitably apertured to receive the outwardly extending main control lever 4U. This lever, as will be described in more detail hereinafter, controls operation of the main driving clutch and alsocontrols selection of forward and reverse driving connections, beingr movable sideways in its lowermost position to effect seanism for the truck, the engine isI indicated generally at I8. The engine is cooledfrom the rau buretor 52 which has the air inlet 53 connected to atmosphere through the air cleaner 54. The fuel supply tank 55 is mounted on the top of the transmission housing 56, and the inlet 51 thereof is protected by the sealing closure 58. n The engine is preferably a standard automotive engine, especially adapted forthis type of work and may be, for example, a six-cylinder engine having governor means which controls its maximum speed of operation. fan 59 is driven from a pulley on the crank shaft of the engine through the fan belt 60, which also drives a suitable pulley 62 for driving the generator 63. A suitable distributor of any standard type is indicated at 64 and has the leads 65 connected to the various spark plugs lfor the engine cylinders.' The engine is supported'upon the side frame members 66 by means of the supporting brackets. 61, these sideframe members extending forwardly as indicated at 68 to provide support for the transmission housing 56. 'I'he panel l5 is supported and braced from the transmission housing 56 by means of the tie rods 69 secured to suitable brackets 10 bolted to the housing. The oil inlet for the engine -crank case is indicated at 12 and is provided with the y'usu type of breather cap 13.

The housing which receives the shaft rotated by the steering wheel 26 is indicated at 14 and is suitably bolted to the inner face of the panel.

I5, the vertical steering shaft 21 extending upwardly into the housing 18 and being geared to the shaft of the steering wheel in a manner similar to the connection at the lowerend of th steering wheel'of an automotive vehicle. A

An oil reservoir is provided at 15, and is supLv ported in any suitable manner. on the engine.

having the T connection 16 at its lower end provided with the inlet 11 connected to the flexible pipe 18 leading from the exhaust outlet `of the valve housing .19, and having an outletLcon'- nectio'n 80 communicating with the oil.pumpv chamber 82. From the chamber 82 an outlet connection 83 is provided leading throughtheflexible pipe 84 to the inlet 85 of the lift-control- This housing is mounted in valve housing 19. suitable manner uponthe top of the pumpcylinder 9 and controls operation of the pump.

The oil supply for the pump cylinder is sepafrate and independent of the oil supply for the crank case of the engine, the crank case oil being connected to the usual oil filter 86 in a well known manner. the horn controlled by the horn button 31 is mounted on the top of the engine adjacentthe forward end thereof, and is indicated at 81;

Referring now to Figure 4 which is-a vertical sectional view through the `transmission unit, the housing 56, which, at' its forward end is provided with the flange 89 adapted tobe bolted to the rear of the engine block 88, is provided at its top with an opening -90 for accessto the interior of the housing,this opening being closed by a suitable plate 92 bolted thereto at its for.-

ward end. The housing has a suita'ble opening which receives the enlarged end 93 nf the'drlving shaft. This end has the ange portion 94 adapted to receive the flywheel member 95, which is suit- -ably centered and bolted .rigidly thereto. The

flywheel 95 has a central opening which receives the ball-bearing assembly 96 in .which the inner The engine means connected to the oil For the sake. of convenience.

end 91 of the main clutch shaft 98:'isv journaled. At its outer periphery, the member 95. is provided with a shouldered face 99 to which is bolted the outer clutch casing |00. The clutch assembly, indicated generally at |02, is of the multiple disc type and is of ample capacity to take the full motor torque. The inner clutch member |03 is engine. A second suitable ring gear |09 is-riveted' to the side-face of the plate 95 and is adapted to have driving engagement with suitable gear .normally urges the. clutch out of clutching engagement. To engage the clutch, a thrust'bear- '-ing` ||3 is provided with is adaptedto' engage the outerv face of the thrust y.member ||2 and whichis moved into vpressure engagement therewith by means of. theclutch Lsleeve H0 having oppositely extending arms ||5 adapted to be pump mechanism` to cev engaged bya suitable -clutch yoke for movement to the leftto force the member ||2 inwardly to effect clutching engagement between the members |00 .and |03, directly clutching the shaft 98 to the engine flywheel'plate 95. v

The ,clutch yoke is actuated by means of the rock shaft i6 extending outwardly of the housing 56, as shown in Figure 3, and having the arm ||1 keyed thereto.. Connected to the arm ||1 is the yoke member ||8'which,'through the tie rod onthe hub of the gear member |25', which is freely rotatable about theshaft 98 on the roller bearings |26. The member |25 has the external helical gearportion |21 ,and the internal clutch tooth portion |28. A second gear member |29 is also mounted on the shaft 98 by means of' the roller' bearings 30,v and is -held against movement outwardly of the shaft by means of the plate |32 bolted to theend of the shaft. The` gear |29 is suitable journaled in the e'ncl of the housing 56 by means of the ball-bearing assembly H9, is connected to a second yoke member |20 |33, the outer race of the assembly being locked innposition by means of the cap plate |34 threaded in the bearingring |35 which is bolted in the end face of the housing.v The inner race of the assembly |33 locked between the shoulder on the gear |29`and the end plate |32.. The 4gear |29 has the outer helical gear" portion |36- and the internal clutch tooth portion |31. The shaft 98 between the gearst |25 and |29 is splined, as

indicated at |38, and receives a suitable clutch sleeve|39 having the clutch tooth portions |40 and |02 which have clutching engagementA with the teeth `.|28 and |31, respectively, uponaxial is provided with a groove |43 adapted to receive Vmovement of the member |39. The clutch sleeve n the tie rod |41 connected at its opposite end through the yoke |48 to the speed control member 38 which projects through the panel |5 and, upon upward movement, rocks the arm in a counterclockwise direction to move the clutch |39 into engagement with the gear |25 to effect low speed driving engagement of the transmission. Upon moving the member 38 inwardly with respectl to the upright, the arm |45 is rocked in a counterclockwise direction to engage theclutch |39 with the gear |29 to effect high speed driving engagement of the transmission.

Disposed beneath the shaft 98 is a second shaft which forms a countershaft jlournaled in the bearing assemblies |52 and |53. Bearing assembly |52 is carried by an upstanding journaled ange |54 formed integral with the housing 56. The shaft |50 is provided at its ends with lock nuts |55 preventing axial movement thereof in the bearings |52 and |53. A gear |56 keyed to the shaft at |51 is adapted to have meshing engagement with the gear |25 andis driven thereby when the clutch |39 is moved into clutching engagement with the gear |25. A second gear |58 is keyed to the shaft |50 at |59 and has driving engagement with the gear |29. A suitable spacing sleeve |60 is disposed between the gears |56 and |58, and serves to maintain these gears in proper driving position with respect to the gears |25 and |29. A suitable cap plate |62 is secured to the' end face of the housing 56 and closes the end of the shaft |50. l. Low speed driving engagement of the clutch |39 provides for driving of a countershaft 50 from the flywheel 95 through the gears |25 and |56. High speed driving engagement is effected through the gears |29 and Disposed below the shaft |50 is the main driven shaft which has a gear |66 mounted thereon by means of roller bearings |61. 'Ihe gear |66 is journaled for rotation with respect to the housing by means of the bearing assembly |61 retained in position by the closure plate |68 bolted to the forward face of the housing. The shaft |65 also carries the -gear |69 mounted thereon by roller bearings |10 and held against axial movement by means of the thrust washer |12 and the end plate' |13 bolted to the end of the shaft. 'I'he gear |69 is journaled in the housing by means of the bearings |14 which are held in position by the closure plate |15-bo1ted to the rear face of the housing 56.

Intermediate the bearings |61 and |10, the shaft |65 is splined, as indicated at |16, which is adapted to receive the clutch collar |11 which is axially movable thereon. Each of the gears |66 and |69 has corresponding internal clutch tooth portions |18 and |19, respectively, which are engaged by corresponding clutch portions The collar and |82 of the clutch collar |11. |11 is provided with an intermediate annular groove |83 receiving the ears |84 ofa clutch yoke |85 carried on the rock shaft |86. The rock shaft |86 projects outwardly of the housing 56 through the sleeve which is keyed to the hub |44 of the arm |45. Clamped tothe outer end of the shaft |86 is a rock arm |81 which, at its extending end, is connected to the yoke |86 that 'ential housing 2 6.

has coupling engagement through the rod |89 with the yoke |90 connected to the arm |92 carried at the lower end of the shaft |93 that extends vertically. upwardly and is journalled at its upper end in the bracket |94 forming part of the frame plate 39. At its lower end the vshaft |93 is journaled in a bracket |95 bolted to the rear face of the upright |5.

The shaft |93 at its upper end has keyed thereto the arcuate segment |96 which, at its upper end, is journaled to a stub shaft also carried by the upper 'portion |91 of the bracket |94. The arcuate segment |96 has a longitudinal slot |98 therein which receives the extending tongue portion |99 of the control lever 42. The control lever 42is pivoted for lateral swinging movement about a stub shaft 200 carried in a bracket 202 formed integral with the shaft |23 whereby the lever 42 has substantially universal pivotal mounting due to its rocking movement on the shaft |23 for vertical movement, and is pivotally mounted on the stub shaft 200`for" lateral swinging movement withrespect to the shaft |23 regardless of its angular position. Thus, when the lever 42 is rotated in a. clockwise direction about the stub shaft 200, the tongue |99 engaging the sides of the slot |98 rotates the arcuate segment |96 in a clockwise direction and thus effects clockwise rotation of the shaft |93. This results in angu- I lar movement of the end of the arm |92 producing longitudinal movement of the rod |89 to the right as shown in Figure 3, land thereby producing counterclockwise movement of the arm |91 to move the clutch collar |11 into clutching engagement with the gear |69. Between the gear |69 and the gear |58, there is. provided an intermediate gear mounted on a reverse' idler shaft disposed laterally outwardly of the plane of the shafts |50 and |65 and journalled inthe bearing cap 208. This effects reverse rotation of the shaft |65 to provide for reverse drive of the vehicle'.

Since either the gear |56 or |58 can rotate the countershaft |50, it is obvious that reverse drive in both low and high speeds is accomplished when the clutch collar |11 is shifted to clutch the gear |69 to the shaft |65. When the lever 42 is rotated in a counterclockwise direction, it effects corresponding rotation of the segment |96 which in turn,.through the shaft |93 and tie rod |89,.

ward and reverse drives in either Aof the two speeds are provided.

The outer projecting end 2|0 of the shaft |65 is keyed into the hub portion 2|2 of a universal coupling yoke 2|3 which has coupling engagement with the corresponding yoke 2|4, completing the universal coupling.

Referring now in detail to Figure 5 which shows the extension of the .drive from the transmission unit to the axle, the universal coupling comprising the yoke members 2|3 and 2|4 couples the shaft |65 to the propeller shaft 2|5 which extends through the upper portion of the differ- The housing 2|6 is provided with a journaled portion 2|1 carryingthe 'tapered roller bearings 2|8 for journaling the shaft 2|5 for rotation therein. The extending indicated at 220. A suitable closure plate 222 holds the bearing assembly 2|8 in position and engages about the hub portion ofthe yoke 2|4.

' thereof.

in the" Suitable oil sealing means 223 is disposed recessed portion of the plate 222.

The shaft 215 at its opposite end is provided with a reduced portion 224 which receives the brake drum 225 keyed thereto as shown at 226. The shaft 224 is journaled in a rear extension '221 of the differential housing by means of bearings 228, these bearings being locked into position by the plate 229 carrying the oil sealing means 239.

'Ihe extension 221 of the housing 216 provides a support for a suitable bracket 232 which carries the brake band pivot members 233 supporting the brake bands 39 and 32 for engagement with the drum 225. This'brakeis of the usual type of external band brake having the free ends thereof provided with brackets 234 as shown in Figure 6 normally urged together by the relatively heavy coiled spring A235 carried by the through bolt 236 extending between the brackets.

A suitable spreading wedge 231 is carried upon a stub shaft 238 supported in the bracket 239 secured to the rear face of the extension of the differenti keyed to housing and a crank arm 249 is spring pressure to release the brake. The crank arm 249 is connected in any suitable manner to the shaft which is rotated by depression of the brake pedal 29.

Intermediate the journal bearings 228 and the differential housing 216, the shaft 215 is provided with a gear portion 242 which has meshing engagement with a gear 243 keyed at 244 to the pinion shaft 245 extending from the rear of the differential casing 216 intothe axlecasing and having the drive pinion 246 at the inner end The shaft 245 is suitably supported in double tapered roller bearings indicated generally at 241 which are held in position by the bearing retaining member 248 clampedv to the closure plate 249 and fitting in the journal opening in the'rear extension of the housing 216. At its inner end, the shaft 245 is journaled in the roller bearings 259 carried by the housing 216. It will thus be apparent that a doublereduction drive is effected between the engine and the drive axle regardless of theposition of the clutch 139, the first reduction being effected by the gears 242 and 243 and the second reduction being effected between the drive pinion 246 and the bevel ring gear 252 shown in Figure 6. The ring gear 252 is bolted to a differential casing 253 of the four-pinion type, which revceives the stub axle shafts 254. The shafts 254 extend through suitable housing members 255 bolted to the sides of the dierential housing 216 and at their outer ends are adapted for splined drive connection with the hub 251 of one yoke '258 of a universaldriving coupling indicated generally at 259. From the coupling 259, the drive extends through the stubshaft 269 to the driving member 262 bolted to the hub portion 263 of the wheel I9.

The hub 263 of the wheel -I9 isjournaled for rotation by means of the tapered roller bearings 264 on the cylindrical portion 265 of a spindle bearing member 266 which has the OpiJQsitely ex'- tending spindles 261 thereof journaled for rotation in the spindle bracket 268 byv means of the bearbe understood that the differential 253 has-two e shaft to effect rotation of the wedge for spreading the brackets 234 apart against the .mounted by links 295 on axle spindles 254 extending in opposite directions and that the wheels I8 are driven therefrom through the coupling 269 and the driving member 262, veach of the wheels being spindle-mounted for Vsteering movement` l 'I'he axle assembly is supported from the frame of the truck by means of leaf spring members 212 extending beneath the housing members 255 and retained by the U-shaped spring yokes 213. The springs 212 at their ends are mounted in suitable shackles 214 bolted to the supporting side frame members 66. By reason of the universal coupling 213, 214, relative movement of the axle assembly with respect to the frame of the truck.

is accommodated, when thevehicle is being driven over uneven road surfaces. The universal couplings 259 intermediatethe ends of the axles allow steering movement of the wheels I9 wlthout interfering with the driving torquetransmitted thereto from the differential 253.

It is to be pointed out that the driving spindles and replenishing this lubricant.

It is to be noted that the housing 216`is made up of two separate complementary cylindricalportions which are piloted together at 285 and are bolted lin sealed engagement by the peripheral ring of bolts 286 extending through the abutting radial flanges 291 and 288 of the complementary members forming the housing 2| 6.

inclusive, directed to the details of the control valve for the pump or lift cylinder, the .housing for the valve is provided with an end cap member 299 having the packing gland nut 292 threaded therein for sealing the external surface of the valve stem 293; The outer end of the valve stem is locked in a block member 294 pivotally an arm 296 keyed to therock shaft 291.

'Ihe shaft 291 is supported in suitable journals carried by the bracket arms 298 formed integral with the plate 299 bolted to the end plate 399 of the cylinder 9. Also secured to the shaft 291 for conjoint rotation therewith is the bell crank 392 having adjustable stops 393 and 394 carriedat the opposite ends of the arms thereof.' The vertical'arm of the bell crank 392 is provided with an offset projecting lug 395 which is connected through the yoke 396 to the longitudinally exis connected through the yoke 398 to an arm 399 carried at one end of a -horizontally extending shaft 319 journaled in the bracket 312 secured to the upright `15. 'Ihe .opposite end of the are mounted in suitable bearing members 289- Y tending rod 391. 'Atits opposite end, the rod 391 shaft is provided with an varm m34/connected l through the rod 314 to the shaft 3I5-upon which thelift leverv 44 is pivoted, as will b'e described hereinafter.

The valve housing 19 is secured to the upper surface of the pump cylinder 9 by means of a plurality of bolts 329 and is aligned in position such that the passageways 322 and 324 are -a'ligned respectively with passageways 325 and part of the lift cylinpiston rod 335 which extends outwardly through the passageway 365 leading from the port 322 the packing gland formed by the socket portion 336 of the head plate 380 and the packing gland nut 331 threaded therein which holds the packing material 338 compressed upon the opposite sides of the metallic bushing 339. Atits outer end the piston rod 335 is provided with a atted portion 348 having rack teeth 342 thereon adapted to have meshing engagement with the gear segment 343 mounted on the shaft 344 extending transversely of the truck frame. The flatted part 340 of the piston rod is guided for movement by the bearing member 345 carried by the supporting bracket 346 secured to the side frame 341 forming a portion of the undercarriage of the platform. When the piston moves outwardly of the cylinder, the shaft. 344 is rotated in a clockwise direction to lower the platform 6 while, when the shaft 344 is rotated in the opposite direction upon inward movement of the piston,

Athe platform is raised throughrock arms and toggle links of the same general construction as described in the aforesaid Burrows, and Burrows and Williams patents.

Considering now in detail the construction of the valve member indicated generally at 19, this member has an outlet port 348 to which is connected the flexible pipe 18 and which communicates within the housing 19 with the main outlet passageway 349 and with the normally extending passageways 356, 352 and 353. 'I'he housing 19 is also provided with a central axially extending cylindrical bore 354 which receives the slidable valve member indicated generally at 355 and preferably formed integral with the valve stem 293.

The end of the bore 354 is closed by the cap member 356 bolted to the face of the housing 19. At its top, the housing 19 is provided with a high pressurejnlet port 351 communicating with the exible pipe coupling 85 and having the main inlet passageway 358. and the normally extending auxiliary passageways 359, 368 and 362 communicating with the bore 354 of the valve housing. In both Figures 14 and 15 the valve is shown in its-neutral position, in which position the enlarged cylindrical portions 363 and 364 close off the passageways 365 and 366 communieating with the ports 322 and 324.

When the valve is moved to the left as shown in Figures 14 and l5, the portion 364 moves into a position opening the passageway 366 and thereby provides communication from the inlet 351 through the passageways 358 and 359 and the reduced portion 361 of the valve to the passageway 366, and thence through the port 324 and the chamber 326 and port 328 to the left hand end of the lift cylinder. At the same time, the enlarged portion 363 of the valve also moves to the left, blocking the passageway 362 leading from the high pressure inlet 351 and opening which is in communication through the passageway 325 with the righthand end of the pump chamber. The passageway 365 under such conditions is in communication with the exhaust passageway 353 around the reduced portion 368 of the valve, and hence fluid from the right hand side ofthe piston 332 is exhausted into the conduit 18 and thence to the T connection 16. The passageway 352 at this time is in communication with the annular chamber 369 and exerts equal pressure against the enlarged anges 310 and `312 of the valve, neutralizing any tendency of the valve to move from this position. At the same time, the high pressure passageway 360 exerts equal pressure against the face of the flange 312 and against the face of the enlarged portion 363 of the valve through the chamber 313 and the reduced portion 314 of the valve so that the valve tends to remain in the position to which it has been moved for lowering the platform. 2

When the valve is moved to the right by actuation of the lever 44 moving the rod 301 forwardly to rock the shaft 291 in a clockwise direction, the valve moves to a position where the enlarged portion 364 closes off communication between the passageway 366 and the passageway 359, and opens communication between the passageway 362 and the passageway 365. 'Ihis delivers fluid under high pressure through the port 322 and the passageway 325 to the right hand en d of the cylinder chamber to move the piston 332 to the left to-raise the platform. At the same time, the enlarged portion 364 of the valve opens communication between the passageways 366 and 350 around the reduced portion 315 of the valve, thereby providing an outlet path through the passageway 350 to the outlet 348. This movement of the valve also effects closing of the communication between passageways 353 and 365 to prevent .exhaust of uid from the passageway 362 into the passageway 353, while allowing the fluid under high pressure to pass through the passageway 362 to the passageway 365. In addition, the enlarged anges 310 and 312 of the valve are moved into position to close off the passageway 369 and. to admit fluid under high pressure through the passageway 368 against the adjacent faces of these anges to hold the valve in a balanced pressure position so that the fluid under high pressure will not tend to move it out of the position to which it has been shifted.

Both of theend flanges 355 andl 316 of the valve are provided with vent openings 311 to..

prevent trapping of oil between the outer faces of these flanges and the ends of the bore 354. Suitable packing 318 iscompressed in position about the external surface of the valve stem 293 by the packing gland nut 292 to prevent any leakage of .oil outwardly along the valve stem.

It is thus apparent that upon pushing the lever 44 downwardly to rock the shaft 3l 5 in a counterclockwise direction, the toggle links 380 and 382, shown in detail in Figures 8 to 10, rock the arm 383 in a counterclockwise direction whereby the shaft 384 is correspondingly rotated to move the rod 385 connected lto the arm 366 carried by the shaft, forwardly of the vehicle. The rod 385 at its forward end is connected through the yoke 386 to the crank arm 381 mounted on the shaft 388 and rotates the shaft 388 in -a clockwise direction to effect -engagement of the pump clutch which will be described in detail hereinafter. As a result, the oil pump operates to pump oil under pressure through the conduit 84 to the high pressure inlet 351. At the same time the rod 3l4 is moved downwardly, which results in forward motion of the rod 301 and consequently moves the arm 296 in a clockwise direction to move the valve into platform raising position. Under such cnditions, oil under pressure is transmitted from the inlet 351 through the passageways 358, 362,-

at its rear end with this housing is closed by the closure cap 403 bolted thereto which forms an end Journal' for the shaft 402. Adjacent its opposite end, the shaft 402 is journaled in a suitable ball-bearing assembly 404 carried by the front face of the housing 56 and also by a portion of the housing 400. A

' suitable gear 405 is mounted on thrust bearings 406 and 401 carried by the reduced portion 408 of the shaft l402, and the housing 4001s provided -with an enlarged portion, 409 enclosing this gear.

The gear 405 has a radially extending external tooth surface having meshing engagement with ably secured in transverse position thereacross.

Asthe platform moves up into the raised position indicated in dotted lines, the vertical back of the angularmember 390 engages the stop 303 and rotates the bell crank 302 in a counterclockwise direction. This, in turn, rotates the shaft 291 which, through the arm 296, moves the valve stem 293 to neutral position, resulting in closing the passageway 362 with respect to the passageway 365 and thus locks the mechanism inplatform-raised position, the pressure in the lift cylinder beingl retained due to the fact' that any exhaust from the passageway 365 `is-'closed oif inthe neutral position of the valve.

When it is desired to lower the platform, the lift lever 44 is raised. This results in raising the rod 3|4 which, in turn, moves the rod 301 rearwardly and pulls on the valve crank 302 to rotate the shaft' 291 in a counterclockwise direction. As

a result, the valve is-moved to the left in the bore 354, and the passageway 365 is opened to exhaustv through the passageway 353. At the same time, the high pressure passageway 359 is placed in communication with the passageway 366 and oil under pressure is admitted therethrough into the left hand end of the lift cylinder, thus positively forcing the pistonto the right to lower the platform. y It will also be noted that when the valve is in neutral position, the clutch mechanism, controlled by the shaft 388 and which will be described in more detail hereinafter, is returned to neutral position to declutch the pump from the driving gears in order to prevent building up of any oil pressure while the valve is in neutral position.l

As the platform is lowered, the under surface of the horizontal portion of the angle member 390 comes into contact with the'stop 304, rotating the valve crank 302 in a clockwise direction and thus moving the arm 296 in a corresponding direction to pull the valve stem 293 into neutral positionl Thus it will be apparent that the upper and lower limits of movement of the platform will automatically result in moving the valve to neutral position and, simultaneously through the connection of the rod 301 to the bell crank, moving the lift lever to a corresponding neutral position, thereby declutching the pump from the drive shaft.

Referring now in detail toFigure 7 which illustrates the manner `in which the pump shaft is driven from the transmission, the ywheel of the transmission has the starting ring gear |08 at its outer periphery and has the smaller ring gear |09 riveted thereto as shown in Figure 4. There is provided a laterally offset housing 400 which is bolted to the side of the transmission housing .as shown in Figure 3. VThe housing 400 'is adapted to enclose the oil pump shaft 402 which extends parallel to the shafts 98, |50 and the gear |09 and driven thereby. Splined on the shaft 402 to the right of the gear 405 is a clutch thrust member 4|0 which is adapted to be moved to the left to produce clutching engagement of the clutch indicated generally at 4| 2. This effects clutching of the-shaft 402 to the gear 405. resulting in rotation of the shaft in accordance with the rate at which the gear is beingdriven by the gear |09. The clutch member 4|0 is actuated by means of the rock shaft 388 which projects into the housing 400 through the offset extension 4|3 and,- within the housing, is connected to the clutch yoke 4|4 which is keyed to the shaft 308 and is rocked in a clockwise direction to move the clutch thrust member 4|0 into position to engage the clutch 4|2 for clutching the gear 405 to the shaft 402. At its end, the shaft 402 is provided with a slotted portion 4|5 which is journaled in the brass bushing 4|6 carried by the cap and the housing 400. The recessed portion .4|5 has engagement with the pump shaft 4|1 upon which is mounted a pump gear member of the usual type (not shown), having meshing engagement with the corresponding gear member mounted on av stub shaft whereby oil from the T connection 16 is drawn between the gear members and is expelled outwardly therefrom under pressure into the outlet connection 83. The pump housing, which is bolted to the housing 400 and is supported laterally of the crank case 88 of the engine,- is indicated at 4|8..

By thus mounting the pump shaft directly on the sde of the transmission housing, no misalignment is occasioned and the shaft can be held in its bearings in proper relation to the driving gear |09. A constantly meshed driving engagement is therefore provided, and the control clutch engages and disengages the oil pump.

Referring now in detail to Figures 8 to 10, inclusive, which show the lever control mounting for operating the pump clutch and lift valve, the lever 44 extends through the panel |5 and through thev frame plate 43 to the forward side of the panel. Mounted on the panel opposite the member 43is the bracket-supporting member 425 which has forwardly extending ear portions 42'6 serving as supports'for the shaft 384 which carries the bell crank comprising the arms 383 and 386.

Disposed above the plane of the shaft 384 is a second pair-of journal supports 421 which support the shaft 3|5 for rotation. The shaft 3|5 serves as a pivot for the lever 44, and the lever 44 has the forwardly extending portion 380 which 'is connected-through the pin 428 with the pair of toggle .links 382 pivotally mounted on their opposite ends by the pin 429 carried by the crank arm 383.

Between the panel I5 and the-shaft 3|5 and within the bracket 425, the lever 44 has a pivot pin 430 which is engaged by the-yoke 432 connected to the shaft-3M. At its upper end the plate bolted to the front face of the housing 56 

